Impact indicator



Patented June 27, 1939 UNITED STATES PATENT OFFICE HHPACT INDICATORHauts Fourneaux de la Chiers, Longwy (Meurthe et Moselle), FranceApplication June 18, 1936, Serial No. 86,012 In France April 17, 1936The direct measurement of the work of an impact member, such as a drophammer, a projectile (shell), etc., moving at a high speed, gives riseto very great difliculties. The present invention relates to anapparatus eflecting such measurements with facility and accuracy.

The apparatus for carrying out the said process is essentiallyconstituted by the combination: of a guide device rendered rigid withthe-impact member subjected to the tests, an inertia member capable offreely moving in this device, a calibrated precision spring compressed(or stretched) by the displacement of the inertia member, a devicerecording the stroke of the inertia member, and, finally, a memberlimiting the upper position of the inertia member.

The apparatus forming the subject-matter oi the invention can receivevarious applications; it can be used every time, considering an impactmember (drop hammer, projectile (shell), etc.) having a high speed, anegative or positive acceleration important relatively to this speed isto be measured.

In order that the invention may be more clearly understood, anapplication of the same to the particular case of the measurement of thework absorbed by the rupture of a rail by means of a drop hammer will bedescribed hereinafter, by way of example only and without therebylimiting in any way the scope of the invention.

The accompanying drawing diagrammatically illustrates, by way of exampleonly, a form of construction of the apparatus forming the subject-matterof the invention.

Fig. l is a section made on line I-I of Fig. 3 and shows the saidapparatus.

Fig. 2 is a partial front view thereof.

Fig. 3 is a section made on line III-J11 of Fig. 2.

In the particular case which will be considered, it is desired tomeasure the number T of kilogrammeters absorbed by the rupture of asection of a rail resting on two bearings, said rupture being caused bythe shock or impact of a drop hammer of known mass freely falling from aheight also known.

As will be seen from the drawing, the appara-' tus which determines thevalue of T, by an indirect method, comprises the following elements:

1. A guide device, which is formed as a cylindrical tube I, secured invertical position by any suitable means, for instance by screwing, tothe upper part of the drop hammer M. This tube is provided, with alongitudinal slot 2.

2. A cylindrical inertia member 111 freely sliding in the tube I andguided in its movement by a projecting screw 3 sliding in the slot 2.

3. A precision spring 4, previously calibrated.

4. A device for recording the stroke or displacement of the inertiamember. In the form of construction illustrated by way of example, thisdevice is made as follows. On either side of the slot 2 are welded,throughout the length of the tube l, two heel pieces 5, 5 in whichlongitudinal slots 6, 6 are provided. A sheet I of thick paper, pressedagainst a backing sheet of metal, can be inserted in the slots 6, 6, andthen held stationary in the required position by means of four setscrews 8. A tracing device 9, constituted for instance by a smallpencil, slides in a housing provided for that purpose in the inertiamember and a very light spring l0 always holds the point of the tracingdevice pressed against the recording paper.

5. A member limiting the upper position of the inertia member andconstituted, in the example illustrated, by an internally screw threadedplug H which is screwed on the upper end of the tube l. The plug l l isscrewed down only until it just contacts the upper end of the member Mso that the force on the spring 4 is that due to member M only.

It is to be understood that the invention is not limited to theembodiment which has been,-.described and illustrated and that variousmodiflcations might be made in the details of construction of theapparatus without departing thereby from the scope of the invention;thus, for instance, the apparatus might be provided with a tensionspring instead of a compression spring, a difierent recording devicemight be adopted, etc. Concerning this device, a. system can be adoptedhaving a ruggedness consistent with the high speeds of impact, thisgiving the possibility of applying the process and apparatus forming thesubject matter of the invention to the study and comparison of theefliciency of armour plates in function of the quality of steelemployed. This particular application is moreover indicated by way ofexample only, and it is to be noted that the process and apparatus areof absolutely general application.

It is also to be understood that the dimensions of the inertia memberand of the spring can vary between wide limits, in view of theadaptation oi the apparatus to the dimensions of the impact member onwhich it is intended to be fitted.

What I claim is:

1. An apparatus for the measurement of the work of an impact membertravelling at high speed comprising an impact member, tubular guidingmeans having a slot therein carried by said impact member, an inertiamember guided in said guiding means, an elastic member connecting saidinertia member to said impact member, a tracing member carried by saidinertia member and projecting through said slot and resilient means formaintaining the tracing member in contact with a tracing paper.

MARCEL AUGUSTIN LEON PERREY.

